Which laboratory tests should be obtained in a patient with newly diagnosed or uncontrolled hypertension?

Laboratory Tests for Hypertension

All patients with newly diagnosed or uncontrolled hypertension should undergo a core panel of basic laboratory tests including: fasting blood glucose (or HbA1c), complete blood count, lipid profile, serum creatinine with estimated glomerular filtration rate (eGFR), serum electrolytes (sodium, potassium, calcium), thyroid-stimulating hormone, urinalysis, and electrocardiogram. 1

Core Basic Testing Panel

The 2017 ACC/AHA guideline establishes the foundational laboratory workup 1:

Essential Blood Tests

• Fasting blood glucose or HbA1c - screens for diabetes, a major cardiovascular risk factor present in 15-20% of hypertensive patients
• Complete blood count - baseline hematologic assessment
• Lipid profile - identifies dyslipidemia (present in ~30% of hypertensive patients)
• Serum creatinine with eGFR - detects chronic kidney disease and establishes baseline renal function
• Serum electrolytes (sodium, potassium, calcium) - screens for secondary causes (hypokalemia suggests primary aldosteronism) and establishes baseline before starting medications
• Thyroid-stimulating hormone - easily detects hypothyroidism and hyperthyroidism as remediable causes of hypertension
• Urinalysis - screens for proteinuria and kidney disease

Essential Cardiac Testing

• 12-lead electrocardiogram - detects left ventricular hypertrophy, atrial fibrillation, and ischemic heart disease 1, 2

This comprehensive panel serves three critical purposes: facilitates cardiovascular risk profiling, establishes baseline values before medication initiation, and screens for secondary causes of hypertension 1.

International Consensus

The 2020 International Society of Hypertension guidelines 2 and 2024 ESC guidelines 3 align closely with these recommendations, emphasizing the same core tests. The most recent 2025 AHA/ACC guideline 4 reaffirms this approach, recommending these tests be repeated at least annually to monitor for medication adverse effects (particularly electrolytes), assess for development or progression of kidney disease, and monitor changes in cardiovascular risk.

Optional Advanced Testing

Consider additional testing when 1:

• Increased hypertension severity
• Poor response to standard treatment
• Disproportionate target organ damage for BP level
• Clinical clues suggesting secondary causes

Optional Tests Include:

• Echocardiography - assesses left ventricular hypertrophy and cardiac function
• Uric acid - elevated in 25% of hypertensive patients
• Urinary albumin-to-creatinine ratio - more sensitive marker of kidney damage than dipstick urinalysis
• High-sensitivity cardiac troponin and/or NT-proBNP - assesses hypertension-mediated organ damage 3

Evidence-Based Minimal Panel

Recent research 5 from 2026 provides the most current evidence on which tests truly benefit patients. The strongest evidence supports routine monitoring of eGFR (to detect chronic kidney disease) and HbA1c (to detect diabetes). This study found good evidence supporting potassium and sodium monitoring, particularly during medication titration with diuretics or renin-angiotensin system blockers 1.

Notably, this research found no or inconsistent evidence for routinely measuring lipids beyond initial assessment, and good evidence of no benefit in routinely monitoring liver function, inflammation markers, or brain natriuretic peptide in stable hypertensive patients 5.

Testing Frequency

• Initial diagnosis: Complete basic panel 1
• Annual monitoring: At minimum, repeat eGFR, electrolytes, and HbA1c 4
• During medication titration: Monitor sodium and potassium levels, particularly with diuretics or RAS blockers 1
• If moderate-to-severe CKD diagnosed: Repeat creatinine, eGFR, and urine albumin-to-creatinine ratio at least annually 3

Common Pitfalls to Avoid

Undertesting is prevalent: A 2025 nationwide cohort study 6 revealed alarmingly low completion rates - only 42.7% had basic metabolic panels, 40.8% had complete blood counts, and just 17% had lipid profiles within 6 months of diagnosis. This represents a significant quality gap in hypertension care.

Medication interference: Be aware that antihypertensive drugs affect laboratory results 7:

• Diuretics (especially thiazides) alter sodium concentrations
• ACE inhibitors and ARBs affect renin-angiotensin-aldosterone system biomarkers
• These effects are expected and should not be misinterpreted as pathology

Clinical impact: A 2025 pilot study 8 demonstrated that patients receiving complete baseline laboratory workups achieved significantly better blood pressure control at 12 months (129.9 mmHg) compared to those with partial workups (142.8 mmHg, P=0.003). Complete testing also unmasked important comorbidities: 8.4% had undiagnosed diabetes, 7.5% had chronic kidney disease, and 54.2% had elevated LDL cholesterol.

Secondary Hypertension Screening

Additional specialized testing should be initiated when clinical or laboratory features suggest secondary causes 1, 2:

• Aldosterone-to-renin ratio - if hypokalemia, resistant hypertension, or adrenal incidentaloma
• Plasma free metanephrines - if episodic symptoms (sweating, palpitations, headaches)
• Late-night salivary cortisol - if cushingoid features
• Renal artery imaging - if flash pulmonary edema, severe resistant hypertension, or abdominal bruit